Mukhtasar Bukhari (Abridged) 2116 — The evil of showing off

It is narrated from Sayyiduna Jundub (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever does a good deed to show off to the creation, Allah will make his bad intention known to everyone (on the Day of Resurrection), and whoever does a good deed to be seen by people, Allah will also show his true reality to everyone on the Day of Resurrection." (And they will not receive any reward.)